CVE-2026-93840
vLLM before 0.29.0 Cross-Request Logits Corruption via allowed_token_ids
- State
- Published
- Severity
- 6.3 Medium
- Published
- Sep 18, 2026
- Updated
- Sep 24, 2026
- Reserved
- Sep 18, 2026
Description
vLLM before 0.29.0 validates allowed_token_ids against tokenizer length instead of model output logits width in SamplingParams._validate_allowed_token_ids(). Attackers can supply token IDs above the output vocabulary that pass validation, causing LogitBiasState to corrupt GPU logits state and allow concurrent requests to sample tokens outside their allowlists.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 6.3 Medium | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N | VulnCheck |
| 3.1 | 3.7 Low | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N | VulnCheck |
Weaknesses
- CWE-129 Improper Validation of Array Index
Affected Products
| Product | Versions |
|---|---|
vllmvllm-project |
|
References
- https://github.com/vllm-project/vllm/pull/49080patchissue-tracking
- https://github.com/vllm-project/vllmproduct
- https://github.com/vllm-project/vllm/commit/5b0e5b69ac1a3884a6479c9537789c95263cc804patch
- https://github.com/vllm-project/vllm/blob/v0.28.0/vllm/sampling_params.py#L881-L903technical-description
- https://github.com/vllm-project/vllm/blob/v0.28.0/vllm/v1/worker/gpu/sample/logit_bias.py#L179-L191technical-description
- VulnCheck Advisory: vLLM before 0.29.0 Cross-Request Logits Corruption via allowed_token_idsthird-party-advisory
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